Means for preventing leakage of fluid through electric cables



Feb. 9, 1943. R. GOLD 2,310,423

MEANS FOR PREVENTING LEAKAGE OF FLUID THROUGH ELECTRIC CABLES Filed Oct.25, 1940 i\\\\\ t W X INVENTOR:

Richard Gold Patented Feb. 9, 1943 MEANS FOR PREVENTING LEAKAGE OF FLUIDTHROUGH ELECTRIC CABLES Richard Gold, Birmingham, England ApplicationOctober 25, In Great Britain 1940, Serial No. 362,847 October 26, 1939 8Claims (01. 17477) This invention has for its object to provide improvedmeans for preventingthe leakage of fluid along the interiors ofelectricv cables.

The invention comprises the combination with a bared portion or portionsof the conductor or conductors which has or have 1: en renderedimpervious by tinning or otherwise, of a rubber sleeve which is mouldedaround the conductor or conductors after the latter has or have beencoated with any convenient binding agent.

The invention also comprises the combination with the bared portion ofthe conductor or one or each of the conductors, of a. rigid core piece.

Further the invention comprises the combination with the bared portionsof a plurality of the conductors, of one or more distance pieces orspacers.

Moreover the invention comprises the combination with the moulded rubbersleeve, of a metal or other rigid sleeve.

In the accompanying sheet of explanatory drawings:

Figure 1 is a sectional elevation of a cable provided in accordance withthe invention with means for preventing leakage of fluid along theinterior of the cable.

Figure 2 is a section ure 1.

Figure 3 is a similar view to Figure l illustrating a modified form ofthe means for preventing leakage of fluid along the interior of thecable.

Figures 4, and 6 are sections taken respectively on the lines 44, 55 and6-6 of Figure 3.

In Figure 1 the inventionis shown applied to a three-core cable a usedfor conveying electrical energy to a submersible pump motor and adaptedto pass through a stufiing box b on the motor casing. This cable itcomprises three stranded-wire conductors c, an insulating sheath orwrapping d on each of the conductors, and an outer or main insulatingsheath e in which the individually insulated conductors are enclosed. Inapplying the invention as shown to the cable a, I remove from that endportion of the cable which is adapted to pass through the stufiing boxb, a convenient length of the insulation d, e so as to bare thecorresponding portions of the conductors. Preferably the removed lengthof each inner insulating sheath or wrapping d is of different length andshorter than that of the main outer insulation e so. as to allow endportions of the inner insulating sheaths or wrappings to project todifferent extents from the adjacent end of the main insulation. To

on theline 2-2 of Figrender the bared portions of the conductors cimpervious to moisture they are tinned or otherwise treated over thewhole or the greater part of their lengths so as to fill up theinterstices between the conductor strands, the filling material beingindicated by f in Figure 2. Where the conductors c are of considerablediameter I may remove as shown in Fig. 1 the bared portion of one oreach a length of its inner strands and replace them by a solid rod 9 ofconvenient diameter and slightly greater length than the removed lengthof conductor strands, the ends of this rod being pointed so that theycan be forced into the adjacent parts of the conductor. The tinning orother treatment above mentioned is effected at least over the length ofthe conductor or conductors from which the inner strands are removed.For holding the bared portions of the conductors c apart in their normalrelationship I place over them one more spacers or distance pieces as hin the form of perforated or slotted discs of cured or partly curedrubber, these being slightly smaller in outside diameter than theexterior diameter of the outer insulation k. Also I place over the baredends of the conductors c, at the position where they enter the motorcasing, a vulcanised rubber or other insulating end block i formed withapertures and short tubular projections (which may be of differentlength) through which the conductors pass. I then mould around the baredportions of the conductors c, between the adjacent end of the outerinsulation e and the insulating end block 1' a sleeve k of uncuredrubber which also surrounds the projecting ends of the inner insulatingsheaths or wrappings d, the distance piece or pieces h and the adjacentportion of the insulating end block, the rubber being caused to enterand completel fill the spaces between the adjacent portions of theconductors. To effect intimate adhesion between the rubber sleeve k andthe outer surfaces of the conductors c the latter are treated with anyconvenient binding agent, such as uncured hard rubber or a solution ordispersion of it or certain rubber derivatives. After the requiredquantity of rubber has been moulded into position it is vulcanised.

In the manner above described I am able to form in that part of thecable a which is adapted to pass through the stufling box 79 aneffective barrier or seal which prevents the creeping along the interiorof the cable any moisture which may gain access to its interior.

To prevent bending of the cable a at the position occupied by the sealabove described, and

to enable the latter to be tightly secured in. the stuiilng box b I mayplace around the rubber sleeve is and the adjacent end portion of thecable insulation e a metal or other rigid sleeve m which is united tothe rubber sleeve in the vulcanising operation after having its interiortreated with a binding agent for effecting intimate adhesion with therubber sleeve, the binding agent being similar to that employed as abovedescribed for treating the bared portions of the conductors c.Preferably the metal or other rigid sleeve m is made in two halves asshown in Figur 2.

;or making a seal between the exterior of the cable a and the stuflingbox 1; through which it enters the motor casing, I may employ a sealsimilar to that described in the specification of my co-pendingapplication No. 362,845"Dynamelectric machines, filed October 25, 1940.Thus, jointing material 11 may be placed in the casing 0 of the stuilingbox and around the metal or other rigid sleeve m on the moulded rubberend portion of the cable. Also placed in the casing o are a pair ofmetal pressure rings p, q which bear against the ends of the jointingmaterial and lit closely the annular space between the exterior of thecable sleeve m and the interior of the easing, the ring q being arrangedon a shoulder r in the inner end of the casing. By means of an annularnut s screwedinto the outer end of the casing 0 endwise pressure is thenapplied to the jointing material 12 through the ring p causing thejointing material to seal the stuffing box effectively and prevent thepossibility of moisture passing through the stufling box to the interiorof the motor.

Figures 3 to 6 illustrate the manner in which.

the invention can be applied to cables of relatively small crosssection. Theiseal shown in this example is applied to the junctionbetween a pair of interconnected cables a, a but it is equallyapplicable to either end or an intermediate porfully reveal the gist ofmy invention that othem can by applying current knowledge readily adaptit for various applications without omitting features, that, from thestandpoint of the prior art fairly constitute essential characteristicsof the generic or specific aspects of my invention, and therefore suchadaptation should and are intended to be comprehended within the meaningand range of equivalency of the following claims.

I claim:

1. In an electric cable, a plurality oi metallic conductors, a pluralityof inner rubber insula-L tions, each of said inner rubber insulationssurrounding one of said conductors, an outer rubber sheath surroundingsaid inner rubber insulations, said inner rubber insulations and saidouter rubber sheath being removed from a part of said cable in such amanner that said inner rubber intion of a single cable. In Figures 3 to6 the cable a is of the three-core round type comprising conductors c,inner insulating sheaths or wrappings d on these conductors, and anouter main insulating sheath 6 as in the previous example, whilst theother cable a is of the three-core flat type comprising conductors cinner insulating sheaths or wrappings 11 and an outer insulating sheathe A convenient length of insulation is removed from the cables a, a attheir adjacent end portions which are then spliced together in anyconvenient manner prior to being tinned or otherwise treated to fill theconductor strands and also treated with a binding agent as in theprevious example, the removal of the insulation being effected so thatthe inner insulating sheaths d, d project towards each other todifferent extents from the adjacent ends of the main insulation e, e Forholding the bared portions of the conductors c, c apart in their normalrelationship I wrap around each interconnected pair of such portions asandwich formed by a sheet u of cured rubber and a similar sheet t ofuncured rubber, the uncured rubber being arranged in contact with thebared conductor portions. The rubber sleeve k is then moulded around thebared portions of the conductors c, c and the spacers t, u, and themetal or other rigid sleeve m is placed around the rubber sleeve priorto vulcanisation. Preferably the rubber sleeve k is made to overlap thadjacent ends of the main insulation e, e as shown.

Without further analysis the foregoing will so sulations project fromthe end faces of said rubber sheath and bared conductor portions areformed between the ends of said inner rubber insulations, and a rubbersleeve vulcanized to said bared conductor portions, to the end faces ofsaid rounding one of said conductors, an outer rubber sheath surroundingsaid inner rubber insulations, said inner rubber insulations and saidouter rubber sheath being removed from a part of said cable in such amanner that said inner rubber insulations project from the end faces ofsaid rubber sheath and bared conductor portions are formed between theends of said inner rubber insulations, a coating of a binding agent onthe outer surface of said bared conductor portions, and a rubber sleevevulcanized to said bared conductor portions, to the end faces of saidrubber sheath, and to the surface of the projecting portions of saidrubber insulations, said rubber sleeve intimately adhering by means ofsaid interposed binding agent to the bared surface of said conductorsand adhering also to the end faces of said rubber sheath and to theprojecting portions of said inner rubber insulations, preventing therebyleakage of fluid along the interior of said cable.

3. In an electric cable, at least one stranded I metallic conductor, theinner wires of which are,

at least partly,-removed, a rigid metallic core arranged within saidstranded conductor and replacing said removed inner wires, a metalliccoating on said wires and to said rigid core filling the intersticesbetween the non-removed wires and said metallic core and between the kwires themselves, making thereby the stranded conductor liquid-tight inlongitudinal direction, and a rubber sleeve vulcanized tov a baredportion of said stranded conductor, said rubber sleeve intimatelyadhering to the bared surface of said stranded conductor and to theouter surface of said metallic coating, preventing thereby leakage offluid along the interior of said cable.

4. In an electric cable, at least one metallic stranded conductor, arubber insulation surrounding said stranded conductor, said rubber cableforming thereby a bared conductor portion, the inner wires of said baredconductor portion being, at least partly, removed, a rigid metallic corearranged within said stranded conductor and replacing said removed innerwires, a metallic coating on said wires and on said rigid core fillingthe interstices between the not-removed wires and said metallic core andbetween the wires themselves, making thereby the stranded conductorliquid-tight in longitudinal direction, a coating of a binding agent onthe outer surface of said bared conductor portion, and a rubber sleevevulcanized to said bared conductor portion between the end faces of saidrubber insulation, said rubber sleeve intimately adhering, by means ofsaid binding agent, to the bared surface of said stranded conductor andto the outer surface of said metallic coating, preventing therebyleakage of fluid along the interior of said cable.

5. In an electric cable of the type claimed in claim 1, in combinationwith the bared portions of said conductors, at least one distancingpiece holding said bared conductor portions in correct position withinthe rubber sleeve vulcanized to them.

6. In an electric cable of the type claimed in claim 1, in combinationwith the bared portions 01' said conductors, at least one distancingpiece having the shape of a perforated or slotted rubber disk throughthe perforations or slots of which said conductors are passing, saidrubber disk being arranged normal to the direction of the conductors andholding said bared conductor portions in correct position within therubber sleeve vulcanized to them.

7. In an electric cable of the type claimed in claim 1, in combinationwith the bared portions of said conductors, spacers made from cured andun-cured rubber sheets sandwiched together and wrapped around said baredconductor portions with the un-cured rubber in contact with theconductors, said spacers holding said bared conductor portions incorrect position within the rubber sleeve.

8. In an electric cable of the type claimed in claim 1, in combinationwith the rubber sleeve vulcanized to the metallic conductor, a rigidsleeve surrounding said rubber sleeve.

RICHARD GOLD.

